Title of Presentation

Determining the Distribution and Abundance of Wintering Red-tailed Hawk Subspecies in Illinois

Type of Submission

Synchronous Poster

Research Field

Biology

Faculty Advisor

Dr. Given Harper

Graduation Year

2022

Start Date

11-4-2021 2:00 PM

End Date

11-4-2021 3:00 PM

Abstract

Red-tailed Hawks (RTH) are one of the most common raptorial birds in North America. Twelve subspecies are recognized, four of which winter in Illinois: Buteo jamaicensis borealis, the predominant subspecies that breeds and winters in IL and eastern North America; B. j. calarus (breeds in western U.S. and western Canada); B. j. kriderii (breeds in northern Great Plains and western Canada); B. j. harlani (breeds in Alaska). In addition, B. j. abieticola (breeds from New England to southeast Alaska) winters in IL and is currently under consideration as a distinct subspecies. However, no systematic surveys have been conducted to determine the winter distribution and abundance of RTH subspecies within the state. Wintering RTH subspecies in IL were documented via analyses of photos of live-trapped hawks (n = 46), photo submissions to eBird (a national repository of documented bird sightings in the U.S.; n = 2142), documentation in Vert Net (listing of RTH study skins in museum collections; n = 131), photos from private individuals, and winter raptor surveys. Analyses of photos of live-trapped RTH indicate that B. j. borealis comprised 93.48% of captures, while 6.52% were B. j. abieticola. B. j. borealis was trapped throughout IL, with 23.26% in northern IL, 65.12% in central IL, and 11.63% in southern IL. In contrast, two of three B. j. abieticola were trapped in northern IL, and one in central IL. This study provides baseline data of the winter distribution of a common raptor within IL, which can aid in understanding how climate change may alter this pattern.

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Apr 11th, 2:00 PM Apr 11th, 3:00 PM

Determining the Distribution and Abundance of Wintering Red-tailed Hawk Subspecies in Illinois

Red-tailed Hawks (RTH) are one of the most common raptorial birds in North America. Twelve subspecies are recognized, four of which winter in Illinois: Buteo jamaicensis borealis, the predominant subspecies that breeds and winters in IL and eastern North America; B. j. calarus (breeds in western U.S. and western Canada); B. j. kriderii (breeds in northern Great Plains and western Canada); B. j. harlani (breeds in Alaska). In addition, B. j. abieticola (breeds from New England to southeast Alaska) winters in IL and is currently under consideration as a distinct subspecies. However, no systematic surveys have been conducted to determine the winter distribution and abundance of RTH subspecies within the state. Wintering RTH subspecies in IL were documented via analyses of photos of live-trapped hawks (n = 46), photo submissions to eBird (a national repository of documented bird sightings in the U.S.; n = 2142), documentation in Vert Net (listing of RTH study skins in museum collections; n = 131), photos from private individuals, and winter raptor surveys. Analyses of photos of live-trapped RTH indicate that B. j. borealis comprised 93.48% of captures, while 6.52% were B. j. abieticola. B. j. borealis was trapped throughout IL, with 23.26% in northern IL, 65.12% in central IL, and 11.63% in southern IL. In contrast, two of three B. j. abieticola were trapped in northern IL, and one in central IL. This study provides baseline data of the winter distribution of a common raptor within IL, which can aid in understanding how climate change may alter this pattern.